Synthesis of Sorbitan Oleate from Sorbitol as Iron Adsorbent and Comparative Capacity of Adsorption on Pectin

Heavy metal pollutant such as iron species is harmful to the environment and the health of living things. The method used in heavy metal adsorption was adsorbent such as bio-sorbents and synthethic adsorbents. In this research, sorbitan oleate was used as an iron (III) adsorbent which aims to determine the adsorption capacity of iron(III) with sorbitan oleate and its ratio to pectin. The synthesis of sorbitan oleate was carried out in two stages: dehydration of sorbitol into sorbitan and esterification of sorbitan with oleic acid to form sorbitan oleate. The greater the synthesis time, the acid number of sorbitan oleic synthesis is smaller. Adsorption of iron (III) ions with sorbitan oleate and pectin was carried out at varied temperature (20 °, 30 °, 40 °, 50 ° Celsius), time (30-180 min), and pH (4, 5, 6, 8, 9 ). There was found an optimum condition for sorbitan oleate at 20 °C, 30 minutes, and pH 4; While for pectin at 20 °C, 90 min and pH 5. Adsorption isotherms iron(III) with sorbitan oleate and pectin both follow Freundlich adsorption isotherms with adsorption capacity of iron (III) with sorbitan oleate and pectin respectively are 1.193 and 0.8304. The interaction of iron (III) ions with sorbitan oleate has a stronger interaction than pectin.